Chemical/mechanical planarization (CMP) is an essential process in the manufacture of semiconductor chips today. During CMP, the combination of chemical etching and mechanical abrasion produces the required flat, precise surface for subsequent depositions. In the CMP process, the semiconductor wafer is retained in a circular carrier head and pressed against a polyurethane polishing pad covered with a chemical slurry. The pressure exerted on the wafer, the rates of rotation of the platen and the carrier head, the chemical composition of the slurry, the temperature of the environment, and the condition of the polishing pad are all closely controlled. The object is to have a repeatable, consistent process each time so that each wafer is as close as possible to an exact copy of every other wafer.
Therefore, every effort is made in semiconductor manufacture to tightly control all factors of the process in order to insure uniformity of the product. Preventive maintenance is therefore a key element. However, one problem has arisen that has not been addressed to date. That is, the carrier heads must be removed from time to time from the mounting flange for preventive maintenance or repair. The carrier head is typically secured to the mounting flange by three pins that extend from the carrier head and mate with cooperating openings in the mounting flange. Over time, because of the close fit between the pins and the openings, the pins or the openings may become slightly damaged. As a result, an interference fit occurs when the carrier head is subsequently installed to the mounting flange. This can cause the carrier head to later resist removal. Of course, other problems such as corrosion, etc., may also make it difficult to remove the carrier head from the mounting flange. Due to the difficulty in removing the carrier head from the mounting flange, the carrier head or other parts of the polishing apparatus can be damaged, which can not only lead to increased manufacturing costs, but it can lead to extended downtime periods as well.
Accordingly, what is needed in the art is a device and method to assist in removing the carrier head from the mounting flange when the carrier head resists normal removal techniques.